A total hip replacement is a reconstructive surgical procedure typically performed by an orthopedic surgeon. A total hip replacement involves placement of an acetabular cup within a patient's acetabular socket and replacement of the patient's femoral neck with a prosthesis which terminates in a ball specifically designed to be positioned in the acetabular cup. Other surgical procedures may require the application of an acetabular cup or other device applied to a patient.
For example, during such acetabular cup procedures, the patient's acetabular socket is reamed out by the surgeon so as to create an enlarged recess to receive the acetabular cup. After the acetabular socket has been reamed, the cup is inserted into the recess and adjusted as necessary to the proper angular orientation. Once deployed, the cup provides a new socket and lining for the patient's acetabulum.
Insertion and placement of the cup by the surgeon is effected either by hand or use of a hand tool that grips the cup. Once the cup is properly positioned in the acetabulum, the cup can be fixed in the desired location by various means such as bone screws, medically acceptable adhesives, or combinations thereof. In many instances, the fixation means include passing bone screws through the cup and into pre-drilled screw holes in the pelvic bone. The bone screws, which are optional, serve to hold the acetabular cup in the acetabulum until bone ingrowth provides permanent fixation.
In one acceptable medical method, the cup is properly positioned in the acetabulum by implantation. One conventional implantation method is to impact an acetabular cup into place after obtaining proper alignment. While impacting the acetabular cup, the surgeon listens for a change in pitch as the cup seats down. The surgeon then probes screw holes to determine if a gap between the cup and the bone is present. If a gap is present, the surgeon further impacts the cup into the acetabulum.
FIGS. 1, 2 and 2A illustrate a conventional spindle-type orthopedic surgical impactor 10. As shown, this prior art impactor 10 has a strike plate 12 that is integrally connected to a proximal end 16 of the impactor body 14. Extending from the strike plate 12 and positioned over a proximal area of the body portion 14 is a fixed handle 18. The fixed handle 18 has a length that allows a surgeon to hold the impactor 10, in one embodiment with one hand, and in an alternative embodiment with two hands. Whatever the fixed handle's 18 length, extending therefrom on the body 14 is an impactor thread section 20. At the body portion's distal end 22 is a tool thread section 24.
The tool thread section 24 threadingly interconnects to a surgical implant device (a.k.a., medical attachment) 26, such as but not limited to an acetabular cup, through a threaded aperture 28 (FIG. 2). That means the implant device 26 is directly connected to the body 14 and the strike plate 12. To ensure the surgical implant device 26 is properly secured to the tool thread section 24, the prior art device 10 uses a rotate handle device 30 (FIG. 2A).
The rotate handle device 30 is positioned in the space between the tool thread section 24 and the impactor thread section 20. At its proximal end, the rotate handle device 30 has a rotating threaded section 32 and at its distal end, an implant support 34. The rotating threaded section 32 has threads that mate with the impactor thread section 20. When the rotating threaded section 32 is rotated clockwise (illustrated by arrow 36 at FIG. 1), (a) the rotating threaded section 32 pushes (illustrated by arrow 38) the rotate handle 30 and the implant support surface 34 toward the surgical implant device's interior surface 40 (FIG. 2); and (b) simultaneously rotates the surgical implant device 26 counter-clockwise (arrow 42 at FIG. 1) through a conventional lock-nut structure of the rotating threaded section 32. This movement results in the surgical implant 26 being pulled toward the implant support 34. Collectively, the clock-wise rotating threaded section 32 is designed to securely position the surgical implant 26 against the implant support 34 to inhibit dislodging of the surgical implant device 26 from the spindle-type tool holder 10 when the surgeon impacts the tool holder.
However, when the surgeon impacts the strike plate 12 there is a possibility that the surgical implant 26 can disconnect from the impactor 10. This could occur when the threaded section 24 or the implant's 26 corresponding threaded section 28 is damaged from the impaction force. Accordingly, what is needed is a firm fixation of the surgical implant 26 during impaction that provides minimal damage to the implant's 26 threads 28. That desired product is achieved with the present invention.